Trotters sign defensive duo

Centre-back Knight, who has won two England caps, joined Villa in the summer of 2007 from Fulham in a £3.5million deal but struggled for regular first-team football, starting just 13 Premier League games last season.

Wales international Ricketts, who can play on the left or the right of a back four, started 27 of the Tigers' Premier League games in their debut season in the top flight.

They are Wanderers boss Gary Megson's third and fourth signings of the summer, with the club having brought in Sean Davis after his contract at Portsmouth expired and also defender Paul Robinson from West Brom.

Megson was delighted with the acquisition of Knight and Ricketts.

"We are really pleased that we could complete the deals. Both players had other offers to consider," the Bolton boss told the club's official website.

"There was a huge amount of work done by the chairman (Phil Gartside), with the support of (owner) Eddie Davies, to make these to happen.

"I am sure that they will fit in to the squad and we are going to make sure that we help them with their new challenge.

"Zat has plenty of Premier League experience and has played at the highest level with England, while Sam personally had a successful debut Premier League campaign with Hull."